A conventional antenna duplexer generally includes a transmission filter and a reception filter. The transmission filter may include a first interdigital transducer (IDT) electrode configured as a transmission resonator on a piezoelectric body. The reception filter may include a second IDT electrode configured as a reception resonator on the piezoelectric body. Each IDT electrode is covered with an insulation layer. U.S. Patent Application Publication No. 2012/0019102 discloses an example of such a conventional antenna duplexer.